Generally, stents are cylindrical medical devices that are implanted to widen or open stenosed portions when lumens inside human bodies are stenosed by diseases developed inside the human bodies and, thus, the functions of the lumens are degraded or the lumens cannot perform any functions.
As a representative, a self-expandable stent is being most widely used. By using the shape memory effect of shape memory alloy, the stent having a cylindrical mesh shape acts to be implanted into a lumen in the state of being contracted to have a small diameter and to then restore its original diameter by means of the shape memory effect and expand a stenosed portion.
Only if the self-expandable stent has expandability for expansion of a lumen, flexibility for flexible adaptation to a bent portion of a lumen while maintaining the bent shape of the lumen without a change, and reducibility for reduction to a predetermined diameter, the stent can appropriately perform its functionality.
A conventional stent constitutes a double stent, in which an inner stent and an outer stent are superimposed on each other and a film-shaped coating is formed, in order to prevent a phenomenon in which the stent is moved from an initial installation location and prevent tissues from growing and invading into a mesh constituting a part of the stent due to the growth of the tissues, thereby preventing stenosis from occurring again. However, the above-described double stent requires an additional connection wire that couples the inner stent and the outer stent to each other. A film is formed through a coating process, and thus the film may be torn when the stent is bent in accordance with the shape of the bent lumen. Accordingly, the conventional stent is problematic in that a manufacturing process is complicated and manufacturing costs are high.
A conventional technology related to the above technology includes “Triple Structure Stent” disclosed in Korean Patent Application Publication No. 10-2012-0098188.